The proposed research will undertake the enumeration and identification of antigenic determinants of gonococcal alpha lipopolysaccharides and the elucidation of the detailed chemical or structural basis of their immunochemical specificity. Specific objectives of this proposal involve the following efforts: 1) To isolate alpha lipopolysaccharide antigens from clinical isolates and laboratory strains of Neisseria gonorrhoeae, by phenol-water extraction and promase treatment. 2) To examine the immunogenicity and prepare antisera against whole killed bacterial vaccines, purified alpha antigen and lipid-free polysaccharide. 3) To examine isolated, purified preparations of alpha antigen for immunochemical purity by immunodiffusion, immunoelectrophoresis, isoelectric focusing, gel filtration and quantitative precipitin analysis. 4) To prepare mon- specific sera for use in microquantitative precipitin studies and quantitative hapten inhibition assay. 5) To determine the chemical composition of purified preparations of alpha antigen and its lipid-free polysaccharide obtained from wild-type and mutant strains. 6) To explore the effects of carbohydrases (alpha and beta glucosidase, galactosidase, N-acetylhexosaminidase) on the immunochemical behavior of antigen. 7) To explore the effect of mild acid hydrolysis on immunochemical reactivity and isolate from hydrolysates, oligosaccharides to be assayed as hapten inhibitors of the precipitin reaction. 8) To screen glucose, galactose and glucosamine containing oligosaccharides of known structure for their ability to quantitatively inhibit alpha-anti alpha systems. The quantitative hapten inhibition method will be used as a molecular probe to elucidate the fine structure of antigenic determinants. 9) To examine gonococcal alpha antigens before and after treatment with mild acid, carbohydrases, and periodate for their ability to cross react with rabbit and horse anti-pneumococcal and anti-Salmonella sera.